Between functional linkages and institutional boundaries

This paper examines functional integration and governance responses between the neighbouring Rhine-Main and Rhine- Neckar metropolitan regions in Germany. This study focuses on processes of corridor-based, axially structured integration that unfold between neighbouring metropolitan regions. Using a mixed-methods approach, the analysis combines longitudinal data on commuter flows, population, and employment (2002–2023) and qualitative insights from expert interviews conducted among regional and state-level planning actors. The results show a clear intensification of functional interdependencies, particularly along the densified north–south corridor connecting both metropolitan regions. However, this development does not translate into increasing integration across metropolitan boundaries. Instead, commuter dynamics remain strongly shaped by distance, size, and hierarchical structures, with growth concentrating in major centres and along corridor axes. At the same time, governance arrangements continue to be fragmented and territorially bounded, resulting in a persistent mismatch between functional spaces and institutional structures. The findings suggest that intermetropolitan integration does not necessarily lead to the emergence of a new governance scale. Rather than megaregionalisation, the case points to the growing importance of flexible coordination mechanisms within existing institutional frameworks.